Homo- and cross-olefin metathesis coupling of vinylphosphane oxides and electron-poor alkenes : Access to P-stereogenic dienophiles

Vinylphosphane oxides 6 undergo catalytic olefin homo-metathesis leading to achiral and P-stereogenic diphosphane dioxides 7 with exclusive (E)-selectivity. Similarly, EWG-substituted vinylphosphane oxides 11, 12 could be prepared with complete (E)-olefin selectivity via olefin cross-metathesis with electron-deficient substrates, such as methyl acrylate and 2-fluorostyrene, using nitro-Hoveyda ruthenium pre-catalyst III. Cross- and homo-metathesis of chiral non-racemic vinylphosphane oxides proceeds without racemization of the phosphorus center of chirality.